Taxonomy

The scientific classification for cetaceans is:


Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Clade: Cetancodontamorpha
Suborder: Whippomorpha
Infraorder: Cetacea


From here it splits back off into the three groups: Mysteceti, Odontoceti, and Archeoceti, and from there the groups go into the families, and the families go into the species.

Classification

There are three major groups from the classification "Cetacea", which includes Mysteceti (baleen whales), Odontoceti (toothed whales), and Archeoceti (Ancient whales). Of these groups there are different families, such as Monodontidae or Eschrichtidae.

Dolphins Vs. Porpoises

Often times when someone sees a dolphin, they will yell out "Look, a porpoise!" While it is true that dolphins look like porpoises, there are some key differences:


Dolphin-

  • Family delphinidae.
  • More pointed dorsal fin.
  • Sharp teeth.
  • Long beak.
  • Large, up to seven meters long.

Porpoise-

  • Family phocoenidae.
  • Very small, blunt beak.
  • More rounded dorsal fin.
  • Rounded teeth.
  • Very small, less than two meters.

Whales, dolphins, and porpoises, oh my!

Believe it or not, cetaceans are much more complex than the simple bottlenose dolphin. There are actually 88 different species of cetaceans, each with unique traits that make them special. Learn more about the classification and the differences between cetacean species! 

Evolution

Like many sea animals, cetaceans did not start out as ocean dwellers. Originally whales, dolphins, and porpoises came from land. To look back at the evolutionary history of cetaceans is to look back at an epic story of survival, trial and error, and most importantly, natures way of moving forward.


The journey of the cetacean begins in modern day India 50 mya. All cetaceans are thought to originate from even-toed ungulates. In fact, their most common ancestor is the hippopotamus! Some of the main stages of evolution that these animals went through are: Indohyus, Pakicetidae, Ambulocetidae, Remingtonocetidae, Protocetidae, and Basilosauridae. Throughout this long evolutionary period, whales and dolphins went from being land animals to growing flukes and fins whilst loosing their legs, developing more stream-like bodies, growing longer faces, and having their nose move from the front of their face to the top of their head


All cetaceans stayed together and followed a singular course of evolution up until 34 mya when there was a split between two groups, Mysticeti (baleen whales) and Odontoceti (toothed whales). These are the two primary groups of modern whales and dolphins.


Differences

Anatomy

While anatomy varies between species to species, in general toothed whales share the same morphology as other toothed whales and baleen whales have the same morphology as other baleen whales. Below are two illustrated examples of the anatomy of toothed and baleen whales.